Wet Limestone FGD-Controls
Wet Limestone
FGD-Controls
Module 6
Welcome Screen
Wet Limestone FGD-Controls Course Overview
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Flue-gas Desulfurization (FGD)
01 02 03 04 05 06
Basics of
SO2&
Related
Regulation
s
Desulfurisation
Technologies FGD
Process
Major
Process
Equipment
Balance of
Plant
Equipment
FGD
Controls
Wet Limestone FGD-Controls
Hi there, I’m Mr. Tech. I
am here to explain all
about Wet limestone
FGD Controls
to you.
Module Overview and Objectives
This slide can be removed if overview is
FGD controls
1Typical DCS
configuration
2Major control loops -
Absorber
3
pH / Reagent feed
control
4pH instrumentation
5Gypsum bleed/ solid
controls
6
Gypsum solids /
density control
7Density
measurement
8Level / make up water
control
9
Booster fan control
10 Emergency quench
11 Summary
12
Assessment
13
Wet Limestone FGD-Controls Topic Introduction
Module Outline
Click on the first icon to start the module.
FGD Controls
Typical System
Configuration
Major Control Loops
Assessment
Wet Limestone FGD-Controls
FGD Controls
Let’s begin by
understanding
what FGD
Controls is.
Topic Introduction
Wet Limestone FGD-Controls Control System and Option Types
Select each box to know the details.
Augmentation of existing Main Plant
Distributed Control System (DCS)
Standalone Programmable Logic Control
(PLC) system
Major and Special Instruments
Continuous Emission Monitoring System
(CEMS)
Let us start with
control system and
options type.
Wet Limestone FGD-Controls
Select each box to know the details.
Augmentation of existing Main Plant
Distributed Control System (DCS)
Standalone Programmable Logic Control
(PLC) system
Major & special instruments
Continuous Emission Monitoring System
(CEMS)
Control System and Option Types
Control and operation of main plant is
carried out through Distributed control
system or DCS
Extending/augmenting this DCS system
is preferred for seamless FGD control,
monitoring & operation from Main Plant
Control room.
Augmentation of existing Main Plant
Distributed Control System (DCS)
Wet Limestone FGD-Controls
Select each box to know the details.
Augmentation of existing Main Plant
Distributed Control System (DCS)
Standalone Programmable Logic Control
(PLC) system
Major & special instruments
Continuous Emission Monitoring System
(CEMS)
Control System and Option Types
PLC control systems are widely considered
for sub systems and relatively smaller
requirements.
If PLC system, it shall be integrated with
Exiting DCS system for remote operation
and monitoring from Main Plant Control
room.
Standalone Programmable Logic Control
(PLC) system
Wet Limestone FGD-Controls
Augmentation of existing Main Plant
Distributed Control System (DCS)
Standalone Programmable Logic Control
(PLC) system
Major & special instruments
Continuous Emission Monitoring System
(CEMS)
Select each box to know the details.
Control System and Option Types
pH analyzer, Density meter, FGD inlet SO2 &
O2 analyzer, lime stone slurry flow
measurement are critical process
parameters.
Major instruments & special
instruments
Wet Limestone FGD-Controls
Select each box to know the details.
Augmentation of existing Main Plant
Distributed Control System (DCS)
Standalone Programmable Logic Control
(PLC) system
Major & special instruments
Continuous Emission Monitoring System
(CEMS)
Control System and Option Types
CEMS is very critical system and it comprises of
multiple analyzers for various parameter SO2,
NO, NO2, CO, CO2, O2, moisture, pressure, flow,
temperature of flue gas monitoring in
compliance to MoEF (Ministry of Environment, Forest and
Climate Change) and pollution board requirements.
It is used for real time air emission monitoring
by Pollution control boards.
Continuous emission monitoring system
(CEMS)
Wet Limestone FGD-Controls Controls, Safety and Redundancy in System
Critical equipment and
process control is
enhanced with triple
redundant parameter
monitoring for all trip
events. All control
measurements are Dual
redundant.
Complete plant
operation and control
parameters (the
parameters used for
automatic control and
operation)is ensured
through redundant
instrument for better
reliability & safety of
FGD plant.
High-tension drives
(powered at 0.6 kV or
higher) are equipped
with a vibration
monitoring system to
ensure man, machine
and process safety.
The complete FGD
plant is designed with
surveillance for both
operational and non-
operational areas and
access control checks
to regulate the plant's
unauthorized entry and
unauthorized
operation.
Wet Limestone FGD-Controls Topic Introduction
Module Outline
Click on the first icon to start the module.
FGD Controls
Typical System
Configuration
Major Control Loops
Assessment
Wet Limestone FGD-Controls
Typical System Configuration
Now, let’s move to the
next to Typical
System
Configuration.
Topic Introduction
Wet Limestone FGD-Controls Typical System Configuration
Select the different levels to know more.
This is the basic
architecture of FGD
control system.
Wet Limestone FGD-Controls Typical System Configuration
Level 0 (Heart of the
control system),
comprising field
instruments,
transducers, sensors
and transmitters. The
major monitoring in the
FGD plant is pH,
Density, SO2,
analysers, flow,
pressure, temperature,
and level transmitters
as major process
parameters.
Select the zoom icon to know more.
Wet Limestone FGD-Controls Typical System Configuration
Level 1 or the
Input/output modules -
This is the part of the
control system that
connects the field
instrument to the
controller/processor of
the control system.
Along with these
modules, marshalling
or termination cabinets
play a major role in the
cabling of the FGD
system.
Select the zoom icon to know more.
Wet Limestone FGD-Controls Typical System Configuration
Level 2
Controller/processor of
the control system is
the control system's
brain. Entire
computing, analysis
and logic are
programmed into this
processor/controller,
which automates the
entire FGD plant.
Essentially, the logic in
controllers is to
interpret the
information relayed by
the transmitter/field
instrument to monitor &
act on the required
plant/equipment/proces
s operation.
Select the zoom icon to know more.
Wet Limestone FGD-Controls Typical System Configuration
Level 3 This layer is
also known as the user
interface level, where
HMI (Human machine
interface) is used for
the operation and
monitoring of the plant
by an operator.
Select the zoom icon to know more.
Wet Limestone FGD-Controls
Which of the following level is known as user interface level?
Select the correct option and click Submit.
Level 0
Level 1
Level 2
Level 3
SUBMIT
Knowledge Check
Wet Limestone FGD-Controls Topic Introduction
Module Outline
Click on the first icon to start the module.
FGD Controls
Typical System
Configuration
Major Control Loops
Assessment
Wet Limestone FGD-Controls Topic Introduction
Major Control Loops
Let’s understand the
Major Control Loops.
Wet Limestone FGD-Controls Major Control Loops List
Now, let us start with
the different kinds of
Major Control Loops.
Bypass Damper control for close
condition
Open Loop Controls
Absorber control loops
Close Loop Controls
Make up water
FGD Trip signals
pH
analyzer
Coriolis type Density meter
Booster Fan
start Control
Booster Fan control
loops
Wet Limestone FGD-Controls Open and Closed Control Loops List
Open Loop Controls Closed Loop Controls
Select each tab to know more.
Wet Limestone FGD-Controls
FGD Start Sequence control
FGD safe shutdown sequence controls
RC Pump sequence start stop controls
Gypsum bleed pump operation Sequence control
Open and Closed Control Loops List
Open Loop Controls Closed Loop Controls
Wet Limestone FGD-Controls
FGD Bypass Damper control
BUF blade pitch control
Absorber Level control
PH and density control in wet lime-stone
Open and Closed Control Loops List
Open Loop Controls Closed Loop Controls
Wet Limestone FGD-Controls
Trip = Unplanned, uncontrolled, ”emergency” shutdown of a machine or process or piece of
equipment.
Example:
High vibration of a piece of rotating equipment, it’s known to “trip” that equipment.
FGD Trip signals
Coming to FGD
Signals.
Equipment/proces
s criticality
Equipment OEM
recommendation
s
Process Safety
The Trip conditions are based on:
Wet Limestone FGD-Controls FGD Trip signals
Failure of all RC
Pumps
Trip
Conditions
for the FGD
plant
Power Black out
Flue Gas Inlet
temperature Hi
Bypass Damper
Open
Both Booster fan
Trip
Absorber Level
Very High
Wet Limestone FGD-Controls Major Control Loops List
Coming to knowing
about Fail Safe
Condition.
FGD plant starts
Sub-system is lined
up
FGD scrubber tower
or absorber is ready
for flue gas entry
Wet Limestone FGD-Controls Bypass Damper control for close condition
At this stage, the flue gas is directed to the absorber through sequential operation, ensuring
permissive conditions for safe operation for equipment to enable the FGD start. Fail safe Conditions
include:
05
03
02
01
04
Booster Fan Inlet / Outlet Guillotine damper open
Two RC pump in operation
Flue Gas Inlet temperature Normal
Flue Gas Inlet pressure not low and High
Accumulator Pressure is normal
Wet Limestone FGD-Controls Booster Fans
Select each tab to know more.
Booster Fan Start Control Booster Fan Control Loops
Let us now learn
about Booster
Fans.
Wet Limestone FGD-Controls
Major Control Loops start the Booster Fans, both the inlet and outlet dampers should be opened and the blade pitch actuator is set
to minimum position.
Any One ID Fan of respective boiler is
running.
Guillotine damper at Inlet/Outlet shall be
closed.
Two absorber recycle pumps are working.
Emergency water storage tank liquid level
above HIGH.
Mist eliminator wash water pump running.
Mist Eliminator water wash cycle in auto-
cycle in Auto.
Bypass Damper is open and Open
feedback available.
Booster Fans
Booster Fan Start Control Booster Fan Control Loops
Wet Limestone FGD-Controls
Axial type booster fan with variable blade pitch actuator converts the positioning signal to a mechanical movement. It
can be interlocked with unit load.
Booster Fans
Booster Fan Start Control Booster Fan Control Loops
Wet Limestone FGD-Controls
Limestone
slurry feed
Make up
water
Gypsum
bleed
Limestone slurry feed
is the limestone slurry
added based on pH
of the absorber slurry.
Makeup water is
based on
absorber level.
Gypsum
bleed is
based on
absorber
slurry
density.
Absorber Control Loops
Coming to Absorber
Control Loops, the
diagram shows control
loops for different inputs.
Wet Limestone FGD-Controls
pH sensor
Piping
pH Transmitter
Field display
pH analyzers are used for measuring pH of
absorber slurry. As well as, controls the limestone
slurry addition in the absorber depending on the
pH values.
Next on list are the pH
Analyzers.
pH Analyzers
Wet Limestone FGD-Controls
Limestone slurry makeup is
added based on absorber
slurry pH.
Outlet SO2can also be used
for controlling limestone slurry
addition.
A pH of 5 to 6 is maintained
inside the absorber.
pH Control loop
pH monitoring is the
next control loop to
cover.
Wet Limestone FGD-Controls
ABSORBER
HIGH-HIGH
HIGH
MEDIUM
LOW
LIMESTONE
SLURRY FEED
VALVE
LOW-LOW
FILTRATE
VALVE
ABOVE
ABOVE
ABOVE
ABOVE
ABOVE
BELOW
BELOW
BELOW
BELOW
BELOW
STOP STOP
STOP
START
MAKEUP WATER
VALVE
MIST ELEMINATOR
WASH SEQUENCE
START
START
Note to SME: No audio has
We will be needing inputs
Absorber Level Control
Wet Limestone FGD-Controls
yes from 0.06 to 2.50
Works on the principles of motion mechanics
Splits when the process fluid enters the sensor
Leads the drive coil to stimulate the tubes to oscillate in
opposition at the natural resonant frequency on operation. As
the tubes oscillate, the voltage generated from each pickoff
creates a sine wave.
Coriolis type Density meter
The Coriolis type
Density meter is next
control loop.
Wet Limestone FGD-Controls
The Density control is based on
the slurry density at the gypsum
bleed pump discharge.
Gypsum slurry will be
discharged into the primary
hydro cyclone feed tank or
recirculated back to the
absorber.
The density range is 1.2-1.3
T/m3 to discharge into the
primary hydro cyclone tank.
Density Control loop
Wet Limestone FGD-Controls Emergency quenching water system
An emergency quench system consists of
an Emergency water tank, auto valve and
spray nozzles.
Quench water from the Emergency water
tank is sprayed into the quenching zone of
the flue gas duct before the absorber takes
it by gravity.
The system is designed to supply
emergency water for 15 minutes and get
activated on the high temperature of inlet
flue gas.
Wet Limestone FGD-Controls
When do the major control loops start the booster fans?
Select the correct option and click Submit.
When both the inlet and outlet dampers are opened and the blade
pitch actuator is set to minimum position.
When the outlet dampers is open and the blade pitch actuator is set to
minimum position.
When the inlet dampers is open and the blade pitch actuator is set to
maximum position.
When both the inlet and outlet dampers are opened and the blade pitch
actuator is set to maximum position.
SUBMIT
Knowledge Check
Wet Limestone FGD-Controls
Which one of the following is based on slurry density?
Select the correct option and click Submit.
Makeup Water
Limestone Slurry
Gypsum Bleed
A and B both
SUBMIT
Knowledge Check
Wet Limestone FGD-Controls
Which of the following does the Emergency quench water
system gets activated on?
Select the correct option and click Submit.
High temperature of flue gas
Tripping of all RC pumps
Low temperature of flue gas
A and B both
SUBMIT
Knowledge Check
Wet Limestone FGD-Controls Topic Introduction
Module Outline
Click on the first icon to start the module.
FGD Controls
Typical System
Configuration
Major Control Loops
Assessment
Wet Limestone FGD-Controls
Assessment
It is time to take
the assessment
now
Assessment
Wet Limestone FGD-Controls Assessment
You have completed the module on Wet Limestone FGD course - Controls and you are ready to take the
module assessment. Please note:
You must complete all questions in one session. If you exit the assessment before all questions are answered,
your answers will not be saved
You need a minimum score of 75% to pass the assessment
You can retry the assessment if you do not achieve the minimum passing score
Good Luck !
BEGIN
Assessment
Test Yourself
Wet Limestone FGD-Controls
SUBMIT
Question 1 of 5
With which of these does the Emergency quench water system get
activated?
Assessment
High temperature of flue gas
Tripping of all RC pumps
Low temperature of flue gas
A and B both
Select the correct option and click Submit.
Wet Limestone FGD-Controls
SUBMIT
Question 2 of 5
Primary hydrocyclone feed is opened at which of the following density
range?
1.8-2.3 T/m3
0.2-0.3 T/m3
1.2-1.3 T/m3
1.6-2.1 T/m3
Select the correct option and click Submit.
Assessment
Wet Limestone FGD-Controls
SUBMIT
Question 3 of 5
Which level is known as the control system's brain?
Level 2
Level 3
Level 0
Level 1
Select the correct option and click Submit.
Assessment
Wet Limestone FGD-Controls
SUBMIT
Question 4 of 5
ME wash system is activated on H-H level of absorber slurry.
True
False
Select the correct option and click Submit.
Assessment
Wet Limestone FGD-Controls
SUBMIT
Question 5 of 5
pH is very crucial parameter for deciding the absorber efficiency.
True
False
Select the correct option and click Submit.
Assessment
Wet Limestone FGD-Controls Assessment
Result
Your score: [ ]%
You have successfully completed the module on Wet
limestone based FGD Control Process.
Click the Exit button to exit the course.
Congratulations!
EXIT
Assessment
Wet Limestone FGD-Controls Assessment
Result
Your score: [ ]%
You need to score 75% or more to pass this assessment.
To retake the assessment, click Retake.
Click the Exit button to exit the course.
Sorry!
RETAKE
Assessment
Wet Limestone FGD-Controls
Thankyou!